Refuse incinerator



Aug. 17, 1965 F. s. SIMPSON 3,200,775

REFUSE INCINERATOR Filed Aug. l2, 1965 2 Sheets-Sheet l Aug. 17, 1965 F.s. slMPsoN REFUSE INCINERATOR 2 Sheets-Sheet 2 Filed Aug. l2, 1963 m .fwW my W5 M M F United States Patent O 3,200,776 REFUSE INCINERATOR FrankS. Simpson, Alton, Ill., assignor to Illinois Stoker Company, Alton,Ill., a corporation of Delaware Filed Ang. 12, 1963, Ser. No. 301,557 6Claims. (Cl. 110-15) This invention relates rto incinerators of the typeemployed in municipal refuse disposal, and m-ore particularly to amethod and apparatus for suppressing re ltravel from the combustion zoneinto an adjacent charging Z-one of such an incinerator.

An incinerator of the character referred to is illustrated by the patentto W. M. Duncan, No. 2,862,463. Such incinerator-s usually have acombustion chamber yfifty or a hundred feet long, the lioor of which isprovided by the upper reach of an endless traveling grate. Between theupper and lower reaches of the traveling grate, provision is made forvforcing air (to support combustion) upwardly through the grate and intothe -bed of burning refuse on it. Under modern operating conditions, thebed of refuse on the traveling gra-te (at the charging end) may have adepth on the order of four or iive feet.

The refuse to be incinerated is a mixture of rubbish with or withoutgarbage-some wet and diiiicultly combustible, 'other very dry and highlyinflammable. While optimum operating conditions are achieved when therefuse is supplied to the incinerator at a rate such as to maintain themaximum depth of bed, this is seldom achieved. The refuse is usuallybrought in by trucks operating on no -xe-d schedule, and discharged intoa deep hopper from the bottom of which it is progressively fed throughan opening into the combustion Zone of the incinerator. The opening hasto be sufficiently large to accommodate passage at a rate such as tomaintain the optimum depth of bed, and (except to the extent that it islled with refuse) the opening is permanently open. When there is :adelay in the arrival of refuse, the supply in the hopper rnay becomedepleted. When the hopper is sufriciently empty that the supply ofrefuse incomple'tely till-s the opening into the combustion zone, or therefuse is loosely packed, dry, and air laden, a condition exists whichinvites combustion to proceed countercurrent to the feed of refuse, backthrough the opening, and into #the hopper. Such can do considerabledamage.

It is an object of this invention to provide a met-hold of preventingthe likelihood of back-travel of tire from the combustion zone of anincinerator through the permanently open charging opening.

According to this invention, the permanently open opening (through whichthe refuse is moved from the hopper in-to the combustion zone of theincinerator) is located above the bed of refuse on the traveling grate;and a current of inert gas is maintained across the opening, inert gas,as here used, means gas which is substantially devoid of 4oxygen in aform which will support combustion. These inert gases may be, andpreferably are, hot flue gases drawn directly from the stack orbreeching of the incinerator and projected athwart the opening so as tosmother any fire that approaches lthe opening. On the other hand, sincet-he inert gases are already hot, they tend to rise toward the top ofthe combustion chamber rather than to blanket the bed of refuse to anextent such as to inhibit its combustion. While such incinerators areusually operated under forced draft through a traveling grate, the locusof ignition is at the top (which is several feet distant from the grate)of the moving bed of refuse, `so that, during operation, the pressure inthe combustion Zone (above the bed) is always somewhat less thanatmospheric. Consequently, the pressure differential on opposite sidesof the opening is such as to draw the injected inert gas toward thestack. T-he curtain formed by the continual projection of inert gas,athwart the opening, also reduces the tendency of air (from the hopper)to flow through any portion of the opening which is unoccupied 'byrefuse, and hence minimize the supply of oxygen to `sustain baciotraveling llame.

Other objects and advantages of this invention will appear from thefollowing detailed description when taken in conjunction with theaccompanying drawings, forming a part thereof, and in which:

FIGURE 1 is a side elevational view partly in section schematicallyillust-rating an incinerator equipped with a device to suppress ignitionand subsequent flame backtravel into the feeder;

FIGURE 2 is a fragmentary elevational view taken on the line 2-2 ofFIGURE 1 looking in the direction of the arrows; and

FIGUR-E 3 is a fragmentary bottom plan view taken along line 3-3 ofFlGURE 1.

FIGURE 1 illustrates the general arrangement of elements in such anincinerator plant. In this particular arrangement, the incinerator,generally indicated as 10, is located at a lower level 11 of the plant.At a substantial elevation there'above, indicated as 12, is locatedlt-he hopper charging opening 14. Hopper 15 connects with the opening 14and extends downwardly toward the lower level 11. A downwardly inclinedconveyor, indicated as A, forms the bottom of the hopper 1S. Theconveyor A extends downwardly and into the incinerator 1@ through alarge opening 16 in its front wall 17. Within the incinerator 10, andwel-l below opening 16, is a traveling grate B extending from adjacentthe front wall 17 to an ash discharge opening at the discharge end ofthe grate B. Hopper 15 has a top wall 19 inclined downwardly in parallelrelation with the upper run of conveyor A and spaced rtherefrom adistance from four to live fee-t. The downwardly inclined wall 19terminates adjacent the front wall 17 at the top of opening .16. Opening16 extends for the full width of conveyor A, and for a distance above itsuiiicient to pass refuse at a rate such as to maintain the optimum `beddepth on grate B.

The top surface of the upper reach of conveyor A forms the floor ofopening 16, and it is preferred that the elevation or such surface(where it traverses opening 16) be above the top of the bed of refuse ongrate B-which, as aforesaid, is usually four or ve feet deep.

Above the grate B is the combustion chamber 20 of the incinerator, andthis in turn is connected directly with the breeching 22 and the stack24. Gases from the combustion pass through the breeching, or flue, 22into the stack and create `a natural dra-ft which maintainssubatmosphe-nic pressure in .the combustion chamber.

Below the upper run of the grate B is a chamber 26. Air for combustionis supplied to the chamber 26 in the usual manner, at a pressure equalto, or greater than, atmospheric and flows through openings in the grateB. Air ilowing through the openings in the grate B passes through thebed of refuse on the grate B to sustain combustion within the combustionchamber 2d, and the gases of combustion then ow to the stack 24 due tothe natural draft in the stack 24.

Located adjacent the incinerator is a motor-driven blower 36. A duct 39extends from the intake of the blower 36 to the breeching 22 so as tofeed the inert gas from the ue to the blower 36. The discharge duct 38from the blower 36 is connected with a tuyere 4t?, as shown in FIGURE 2.The gases from the tuyere 40 flow into a manifold which frames that partof opening 16 that lies above the upper surface of conveyor A. The manifold consists of a horizontal pipe 42 which in turn is connected at itsopposite ends to two vertical pipes 44 and 46. The lower ends of thepipes 44 and 46 are closed. Pipe 42 has a plurality of orifices 41disposed to direct the jet of inert gas issuing from these oritices inthe direction of the arrow d, shown in FlGURE 1. The pipes 44 and 46have a plurality of orifices 43 and 45, respectively, located to directthe jets of gas along the arrows e and f, respec tively, of FGURE 3. Asshown in FlGURE 1, the pipe 42 is located between the front wall 17 andthe end of the inclined wall 19. Opposite side walls 13 and 13 connectwith the inclined wall 19 and extend downwardly at least as far as thesurface of the upper run of conveyor A. Pipes 44 and 46 are disposedbetween the ends of walls 13 and 1S and the front wall 1"?, as shown inFGURE 3.

For example, when the opening 16 is four feet high and eight feet wide;and the orifices 41, 43 and 45 are in the form of slits (0.3 X 3.0) ofwhich there are twenty in pipe 42, and ten each in pipes 44 and 46, theblower may be such as to deliver 2,000 cubic feet per minute (at ahydrostatic pressure of eight to ten inches) through a discharge duct 3Swhich is eight inches in diameter. This arrangement provides a curtainwhich is thin yet substantially continuous peripherally, and theindividual jets issuing from the several oriiices have suflicientVelocity to maintain substantial continuity across the opening 16 whencompletely void of refuse. When the incinerator is in operation, therefuse is brought in in trucks to the upper level 12 and dumped from thetrucks through the hopper charging opening 14 into the hopper 15 so asto till the hopper with refuse. This refuse, or'rubbish, leaves thehopper through the discharge opening 16 at the speed of travel of theconveyor A. As the rubbish emerges from hopper 15, it is surrounded by acurtain of inert gas llowing in the direction of the several arrows d, eand f. This curtain purges air from about the rubbish in the chargingzone of the incinerator, and, consequently, any highly iniiammablematerial in the rubbish cannot be ignited so that back-travel of flamebetween the walls 13, 18 and 19 of the hopper 15 is suppressed andprevented. As long as there is rubbish to be fed from the hopper 15, thesurface of the conveyor A is protected from the hot gas issuing from theholes 41, 43 and 45. As shown by the arrows d, e and f, these holes areall located to direct the curtain of inert gas toward the combustionchamber 20 where it will be sucked up the stack 24 by natural draft.

The curtain of inert gas discharged by the jets d, e and f, impingesdirectly upon the rubbish at opening 16. Because of the high velocityfrom the orifices 41, 43 and 45, penetration of these inert gases intothe refuse may purge it of entrained air.

Changes in and rnoditications of the construction described may be madewithout departing from the spirit of my invention or sacrificing itsadvantages.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

1. In the art of refuse disposal in an enclosed incinerator having atraveling grate through which air is passed upwardly to supportcombustion on said grate of a deep bed of combustible refuse and saidtraveling grate having an inlet end at which the refuse is deposited onthe traveling grate through a permanently open opening in theincinerator enclosure, the improvement which cornprises, locating saidpermanently open opening at said inlet end of said traveling grate andso that it extends substantially above the top level of the bed ofrefuse on the traveling grate, subjecting inert gas to a pressuregreater than that which exists within said incinerator, and projecting acurtain of said pressurized inert gas athwart said opening.

2. A method for controlling back-travel of Ire in an incinerator havinga combustion chamber with a charging opening, a grate travelinglengthwise beneath said combustion chamber, a feeder discharging throughsaid charging opening chamber adjacent one end of said grate and throughwhich refuse is fed onto said grate, comprising the steps of:

(a) creating a curtain of inert gas around the stream of refuse as itenters said combustion chamber by discharging a series of jet streams ofinert gas in a direction athwart said feeder discharge, and

(b) creating a negative pressure gradient in said furnace in a directionto cause a ow of inert gas away from said discharge into said combustionchamber.

3. A device for conning combustion in an incinerator having an enclosedcombustion chamber normally at subatmospheric pressure, a travelinggrate in said incinerator provided with apertures supplying air to thefuel on said grate and to said combustion chamber, an opening in theenclosure for said combustion chamber at the infeed end of saidtraveling grate, and a feeder for feeding a stream of refuse throughsaid opening onto Said grate, said device comprising,

(a) means located at said opening provided with a series oi orificesadapted to be addressed toward the upper sides of the stream of refusefed through said opening, and

(b) a source of inert gas under pressure connected with said means toproduce a jet ilow from said oriiices,

said orices being located on said means adapted to create a curtain offlowing inert gas at said opening and about the stream of refuse as itmoves into said combustion chamber to inhibit back-travel of flamethrough said opening.

4. In an incinerator having in combination walls forming a combustionchamber, an infeed opening in one of said walls, means to maintain saidcombustion chamber under subatmospheric pressure, a traveling grate formoving burning refuse through said combustion chamber from said infeedopening, apertures in said grate to supply air to said combustionchamber, and a refuse feeder with a discharge end communicating withsaid opening and including a support for the stream of refuse deliveredby said feeder and extending into said combustion charnber above theinfeed end of said grate, the improvement comprising,

(a) means located atsaid opening in said wall and provided with orificesadapted tol be opening toward the upper sides of the stream of refusefed into said furnace through said opening, and

(b) a source of inert gas under pressure connected with said means toproduce a flow from said orifices,

said orices being located on said means adapted to create a curtain oflowing inert gas about the stream of refuse in the vicinity of saidopening to exclude air fed to said combustion chamber from penetratingthe stream of refuse from the combustion chamber to the opposite side ofthe curtain and back-travel of flame over said support into said feeder.

5. The conibinaion as dened in claim 4 in which References Cited by theExaminer said refuse feeder is a vertical hopper and said support UNITEDSTATES PATENTS for the stream of refuse is an inclined endless conveyorforming the bottom of said hopper. 116591564 2/28 Duncan no X 6. In anincinerator having an enclosed endless trevel- 5 1,725,129 8/29C'rPentef et al e- 263-50 ing grate having an inlet end for receiving,supporting, 210641532 12/36 Gllbft 263-50 X and moving a deep bed ofrefuse from end to end there- 116,573 5/38 Haffmgton 1105 of Whileburning with the support of air impelled up- QTHER REFERENCES Wardlythrouh said grate, the improvement which comprises, an erclosure forsaid grate having an infeed German primed applicano 1107365 prmted May10 opening adjacent said inlet end adapted to be located 5 1961 abovethe top level of the maximum bed of refuse, and means for forcing acurtain of inert gas inwardly at said JAMES W' WESTHAVER PrimaryExammer' opening. JO'HN I. CAMBY, CHARLES SUKALO, Examiners.

1. IN THE ART OF REFUSE DISPOSAL IN AN ENCLOSED INCINERATOR HAVING ATRAVELING GRATE THROUGH WHICH AIR IS PASSED UPWARDLY TO SUPPORTCOMBUSTION ON SAID GRATE OF A DEEP BED OF COMBUSTIBLE REFUSE AND SAIDTRAVELING GRATE HAVING AWN INLET END AT WHICH THE RESUSE IS DEPOSITED ONTHE TRAVELING GRATE THROUGH A PERMANENTLY OPEN OPENING IN THEINCINERATOR ENCLOSURE, THE IMPROVEMENT WHICH COMPRISES, LOCATING SAIDPERMANENTLY OPEN OPENING AT SAID INLET END OF SAID TRAVELING GRATE ANDSO THAT IT EXTENDS SUBSTANTIALLY ABOVE THE TOP LEVEL OF THE BED OFREFUSE ON THE TRAVELING GRATE, SUBJECTING INERT GAS TO A PRESSUREGREATER THAN THAT WHICH EXISTS WITHIN SAID INCINERATOR, AND PROJECTING ACURTAIN OF SAID PRESSURIZED INERT GAS ATHWART SAID OPENING.